TP53 and gastric cancer: These include molecules in growth factor pathways (e.g., the human epidermal growth factor receptor 2 (HER2)), regulators of the cell cycle and apoptosis (e.g., the tumor protein p53 (encoded by TP53 gene)), cell adhesion factors (such as E-cadherin), immune checkpoint control modulators programmed death 1 and programmed death-ligand 1 (PD-1/PD-L1), and other molecules relevant to DNA, RNA, exosome, or epigenetic modifications.37,38 HER2 is the first clinically used molecular biomarker for GC patients.